The modelling of underwater noise sources and their potential impact on the marine environment is considered, focusing on tidal turbines in shallow water. The requirement for device noise prediction as part of environmental impact assessment is outlined and the limited amount of measurement data and modelling research identified. Following the identification of potential noise sources, the dominant flow-generated sources are modelled using empirical techniques. The predicted sound pressure level due to inflow turbulence for a typical turbine is estimated to give third-octave-bandwidth pressure levels of 119 dB re 1 μPa at 20 metres from the turbine at individual frequencies. This preliminary estimate reveals that this noise source alone is not expected to cause permanent or temporary threshold shift in the marine animals studied.